静态问题 [英] Problem about Static
问题描述
亲爱的，
我对静态类成员有一点问题，但是找不到
虽然它很容易你能帮我吗？
#include< iostream>
使用命名空间std;
class SavingsAccount {
public：
SavingsAccount（双倍金额）{
savingsBalance =金额;
}
void calculateMonthlyInterest（）{
double mi; //每月利息
mi = savingsBalance * annualInterestRate / 12;
savingsBalance + = mi;
}
static void modifyInterestRate（double newrate）{
annualInterestRate = newrate;
}
double savingsGet（）const {
return savingsBalance;
}
static void setannualInterestRate（double rate）{
annualInterestRate = rate;
}
私人：
静态双年度积分率;
双倍储蓄平衡;
};
int main（）
{
SavingsAccount saver1（2000.0）;
SavingsAccount saver2（3000.0）;
< br $>
SavingsAccount :: setannualInterestRate（3.0）;
saver1.calculateMonthlyInterest（）;
saver2.calculateMonthlyInterest（）;
cout<< saver1.savingsGet（）<< endl;
cout<< saver2.savingsGet（）<< endl;
SavingsAccount :: modifyInterestRate（4.0）;
saver1.calculateMonthlyInterest（）;
saver2。 calculateMonthlyInterest（）;
cout<< saver1.savingsGet（）<< endl;
cout<< saver2.savingsGet（）<<结束;
返回0;
}
utab skrev：亲爱的，
我对静态类成员有一点问题但是找不到它虽然很容易。请你帮助我好吗？
问题是什么？
#include< iostream>
使用命名空间std;
class SavingsAccount {
公开：
SavingsAccount（双倍金额）{
savingsBalance =金额;
}
void calculateMonthlyInterest（）{
双mi; //每月利息
mi = savingsBalance * annualInterestRate / 12;
savingsBalance + = mi;
}
static void modifyInterestRate（double newrate）{
annualInterestRate = newrate;
}
double savingsGet（）const {
return savingsBalance;
}
static void setannualInterestRate（double rate）{
annualInterestRate = rate;
私有：
static double annualInterestRate;
double savingsBalance;
};
double SavingsAccount :: annualInterestRate = 0.0;
< snip>
-
TB @ SWEDEN
对不起，问题是
/tmp/ccBiUko3.o：在功能中
`ReavingsAccount :: calculateMonthlyInterest（） ''：
d2.cc :(。nuu.linkonce.t._ZN14SavingsAccount24calcul ateMonthlyInterestEv [SavingsAccount :: calculateMonthlyI nterest（）] + 0xd）：
未定义引用`SavingsAccount :: annualInterestRate''
/tmp/ccBiUko3.o：函数中
`ReavingsAccount :: modifyInterestRate（double）''：
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount18modify InterestRateEd [SavingsAccount :: modifyInterestRate（double）] + 0x19）：
未定义引用`SavingsAccount :: annualInterestRate''
d2.cc :(。gn.linkonce.t._ZN14SavingsAccount18modify InterestRateEd [SavingsAccount :: modifyInterestRate（double）] + 0x1f）：
未定义引用`SavingsAccount :: annualInterestRate''
/tmp/ccBiUko3.o：函数中
`ReavingsAccount :: setannualInterestRate（double ）''：
d2.cc :(。nuu.linkonce.t._ZN14SavingsAccount21setann ualInterestRateEd [SavingsAccount :: setannualInterestRate（double）] + 0x19）：
undefined reference to `SavingsAccount :: annualInterestRate''
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount21setann ualInterestRateE d [SavingsAccount :: setannualInterestRate（double）] + 0x1f）：
未定义引用`SavingsAccount :: annualInterestRate''
collect2：ld返回1退出状态
:)）
utab写道：对不起，问题是
/tmp/ccBiUko3.o：功能
`SavingsAccount :: calculateMonthlyInterest（）''：
d2.cc :(。nuu.linkonce .t._ZN14SavingsAccount24calcul ateMonthlyInterestEv [SavingsAccount :: calculateMonthlyInterest（）] + 0xd）：
未定义引用`SavingsAccount :: annualInterestRate''
（另外5个引用相同变量的地方）
好吧，正如所有错误消息所说，问题很简单。
SavingsAccount :: annualInterestRate未定义;所以定义它。
HTH，
Michiel Salters
Dear all,
I have a little problem about static class members and could not find
that though it is very easy. Could you please help me?
#include <iostream>
using namespace std;
class SavingsAccount{
public:
SavingsAccount(double amount){
savingsBalance=amount;
}
void calculateMonthlyInterest(){
double mi; // monthly interest
mi=savingsBalance*annualInterestRate/12;
savingsBalance+=mi;
}
static void modifyInterestRate(double newrate){
annualInterestRate = newrate;
}
double savingsGet() const{
return savingsBalance;
}
static void setannualInterestRate(double rate){
annualInterestRate=rate;
}
private:
static double annualInterestRate;
double savingsBalance;
};
int main()
{
SavingsAccount saver1(2000.0);
SavingsAccount saver2(3000.0);
SavingsAccount::setannualInterestRate(3.0);
saver1.calculateMonthlyInterest();
saver2.calculateMonthlyInterest();
cout << saver1.savingsGet() << endl;
cout << saver2.savingsGet() << endl;
SavingsAccount::modifyInterestRate(4.0);
saver1.calculateMonthlyInterest();
saver2.calculateMonthlyInterest();
cout << saver1.savingsGet() << endl;
cout << saver2.savingsGet() << endl;
return 0;
}
utab skrev:Dear all,
I have a little problem about static class members and could not find
that though it is very easy. Could you please help me?
And the problem is?
#include <iostream>
using namespace std;
class SavingsAccount{
public:
SavingsAccount(double amount){
savingsBalance=amount;
}
void calculateMonthlyInterest(){
double mi; // monthly interest
mi=savingsBalance*annualInterestRate/12;
savingsBalance+=mi;
}
static void modifyInterestRate(double newrate){
annualInterestRate = newrate;
}
double savingsGet() const{
return savingsBalance;
}
static void setannualInterestRate(double rate){
annualInterestRate=rate;
}
private:
static double annualInterestRate;
double savingsBalance;
};
double SavingsAccount::annualInterestRate = 0.0;
<snip>
--
TB @ SWEDEN
Sorry for that the problem is
/tmp/ccBiUko3.o: In function
`SavingsAccount::calculateMonthlyInterest()'':
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount24calcul ateMonthlyInterestEv[SavingsAccount::calculateMonthlyInterest()]+0xd):
undefined reference to `SavingsAccount::annualInterestRate''
/tmp/ccBiUko3.o: In function
`SavingsAccount::modifyInterestRate(double)'':
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount18modify InterestRateEd[SavingsAccount::modifyInterestRate(double)]+0x19):
undefined reference to `SavingsAccount::annualInterestRate''
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount18modify InterestRateEd[SavingsAccount::modifyInterestRate(double)]+0x1f):
undefined reference to `SavingsAccount::annualInterestRate''
/tmp/ccBiUko3.o: In function
`SavingsAccount::setannualInterestRate(double)'':
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount21setann ualInterestRateEd[SavingsAccount::setannualInterestRate(double)]+0x19):
undefined reference to `SavingsAccount::annualInterestRate''
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount21setann ualInterestRateEd[SavingsAccount::setannualInterestRate(double)]+0x1f):
undefined reference to `SavingsAccount::annualInterestRate''
collect2: ld returned 1 exit status
:))
utab wrote:Sorry for that the problem is
/tmp/ccBiUko3.o: In function
`SavingsAccount::calculateMonthlyInterest()'':
d2.cc:(.gnu.linkonce.t._ZN14SavingsAccount24calcul ateMonthlyInterestEv[SavingsAccount::calculateMonthlyInterest()]+0xd):
undefined reference to `SavingsAccount::annualInterestRate'' (5 more places in which the same variable is referenced)
Well, as all the error messages say, the problem is simple.
SavingsAccount::annualInterestRate is undefined; so define it.
HTH,
Michiel Salters
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